This is the playdough recipe I use for my kindergartners. I made it this morning for Elinor and she loves it.
2 cups flour
1 cup salt
2 TBSP vegetable oil
4 tsp cream of tarter
2 cups water
Food coloring of choice
Place all ingredients in medium saucepan. Cook over medium heat, stirring constantly, until mixture thickens and forms a ball (this only takes a minute or two).
Remove from pan and cool on counter.
When cool (I don't let it completely cool, but mostly), knead for 1 minute. Store in air tight container.